1. Field of the Invention
This invention relates generally to a packaging assembly for a photonic device that employs a bulkhead connector and, more particularly, to a method of aligning an optical fiber to a photonic device with sub-micron accuracy in a packaging assembly that employs a bulkhead connector.
2. Discussion of the Related Art
Certain photonic devices having small active areas, such as photodetectors, laser diodes and optical modulators, are sometimes mounted within a cavity of a housing as part of a device packaging assembly. For high frequency applications (&gt;1 GHz), a detachable connector is needed for single mode or polarization maintaining fiber at 1310/1550 nm wavelengths to a hermetic package. An optical fiber is coupled to the photonic device to transmit optical signals applied to or generated by the device through the housing. The end of the optical fiber proximate the photonic device typically includes a lens for efficient optical coupling between the photonic device and the fiber to reduce optical losses. The fiber extends through the housing and is attached to a specialized connector adaptor, such as an FIS connector adaptor. The end of the fiber positioned within the connector is typically a bare fiber that is polished. The connector adaptor can be attached to a connector in a threaded or snap-fit engagement that aligns the polished end of the fiber with another fiber to connect the photonic device to an optical system.
The known packaging assemblies for a photonic device generally include a length of fiber extending from the housing that is attached to the connector adaptor. This length of fiber is generally referred to in the art as a fiber pigtail. Typically, this fiber pigtail is &gt;1 foot in length. The fiber pigtail is a weak link in the packaging of the photonic device because it has a tendency to be easily damaged or broken. When the fiber pigtail breaks or becomes defective, the entire packaging assembly, including the photonic device, becomes useless and must be replaced. Therefore, the fiber pigtail is a source of increased cost and unreliability for the optical system.
The tensed end of the fiber must be optically aligned with the photonic device. Sometimes the photonic device must support single mode or polarization maintaining, single mode fibers. In these types of applications, it is generally necessary to align the fiber to the photonic device within the housing with sub-micron accuracy. Automated alignment and laser welding systems are known in the art, such as the Newport Corporation laser weld workstation (LWWS), that provide this level of alignment accuracy for the fiber pigtail type design. In a typical alignment process, the fiber is soldered to the ferrule, and then the LWWS aligns the lensed end of the fiber to the photonic device. The photonic device is previously soldered to the housing. The article, Jang, Soon, "Packaging of Photonic Devices Using Laser Welding," Society of Photo-Optical Instrumentation Engineers, Vol. 2610, May 1996, pgs. 138-149 discusses the LWWS.
What is needed is an improved method of aligning a fiber to a photonic device with sub-micron accuracy within a packaging assembly of the type described above that eliminates the fiber pigtail. It is therefore an object of the present invention to provide such a method.